Halifax at Evere Belgium
Engines Used in Halifax Variants
Early Development & The Vulture Engine
- The initial design for the Halifax, then known as the HP.56, was intended to be powered by the 2,000 hp Rolls-Royce Vulture engine, a novel X-configuration engine formed by combining two Kestrel engines.
- This ambitious engine choice was mandated by the Air Ministry in the P.13/36 specification, despite the Vulture still being under development and posing a significant technical risk.
- The Vulture’s unreliability ultimately led to its abandonment, impacting the development of both the Halifax and the Avro Manchester, which also relied on this engine.
The Merlin Era
- With the failure of the Vulture, Handley Page explored various alternative engine options, eventually settling on the Rolls-Royce Merlin engine.
- The Halifax Mk I, the first production variant, was initially equipped with four Merlin X engines, each generating 1,145 hp.
- Subsequent variants, including the Mk II and Mk V, saw the adoption of more powerful Merlin XX (1,280 hp) and Merlin 22 (using 100-octane fuel at +7 psi boost) engines, enhancing performance and allowing for increased all-up weight.
Transition to Radial Engines: The Hercules
- The desire for improved performance, particularly at high altitudes, led to consideration of radial engines, specifically the Bristol Hercules.
- The Halifax Mk III, the most numerous variant, marked a significant shift, being powered by four 1,615 hp Hercules VI or XVI radial engines.
- This engine choice gave the Mk III a significant performance boost compared to its Merlin-powered predecessors, achieving speeds and operational ceilings comparable to, and in some cases exceeding, the Lancaster.
- Further refinement came with the Halifax Mk VI, which utilized the Hercules 100 engine, offering enhanced performance through its use of 100-octane fuel and an RAF-Hobson injector-type carburetor.
- The final bomber variant, the Halifax Mk VII, utilized the Hercules XVI engine, similar to the Mk III.
Halifax Variants and Their Engines
- Mk I: Four Rolls-Royce Merlin X engines
- Mk II: Four Rolls-Royce Merlin XX or 22 engines
- Mk III: Four Bristol Hercules VI or XVI radial engines
- Mk IV: (Project only, not built): Four Rolls-Royce Merlin 60 series engines
- Mk V: Four Rolls-Royce Merlin XX or 22 engines
- Mk VI: Four Bristol Hercules 100 radial engines
- Mk VII: Four Bristol Hercules XVI radial engines
- A.IX: Four Bristol Hercules XVI radial engines
- A.X (Project only, not built): Four Bristol Hercules 100 radial engines
The transition from the troublesome Vulture to the reliable Merlin and ultimately the powerful Hercules engines significantly impacted the Halifax’s performance and operational capabilities. The adoption of the Hercules, in particular, transformed the Halifax into a truly formidable bomber, allowing it to carry a substantial bomb load at high altitudes and speeds comparable to its more celebrated counterpart, the Lancaster.